This is the first public appearance of his campaign for reelection. So far it's consisted mostly of increased repression against the free media and systematic harassment of opposition activists, including arbitrary arrests and even torture. There are also veiled threats from both the military top brass and the Ministry of the Interior against the so-called "NATO agents" in Yugoslavia, which is how they describe the opposition. It's been the dirtiest campaign ever from the government side. Previously, the government refrained from systematic use of violence against the opposition during elections, but not this time.
The opposition knew they'd have no access to the electronic national media, so they're doing a door-to-door campaign. Kostunica visits five or six towns each day, speaking in public places and drawing huge crowds. So far the government hasn't tried to stop him from campaigning in this way, because that would destroy any legitimacy they're trying to achieve by holding the election.
So Kostunica is far ahead in the polls. Will he get more votes than Milosevic on election day? Yes. But will Milosevic recognize that fact? No. Milosevic will declare victory in the first round, and anyone who has any complaints will be told to take the matter to an electoral commission or courts controlled by Milosevic. And also warned that any other form of protest will be ill-advised.